<div class="refentry" title="glPixelStorei"><a id="glPixelStorei"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glPixelStorei — set pixel storage modes</p></div><div class="refsynopsisdiv" title="C Specification"><h2>C Specification</h2><div class="funcsynopsis"><table class="funcprototype-table"><tr><td><code class="funcdef">void <b class="fsfunc">glPixelStorei</b>(</code></td><td>GLenum <var class="pdparam">pname</var>, </td></tr><tr><td> </td><td>GLint <var class="pdparam">param</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1" title="Parameters"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term">
                    <em class="parameter"><code>pname</code></em>
                </span></dt><dd><p>Specifies the symbolic name of the parameter to be set.
                    <code class="constant">GL_PACK_ALIGNMENT</code>
                    affects the packing of pixel data into memory.
                    <code class="constant">GL_UNPACK_ALIGNMENT</code>
                    affects the unpacking of pixel data
                    <em class="parameter"><code>from</code></em> memory.</p></dd><dt><span class="term">
                    <em class="parameter"><code>param</code></em>
                </span></dt><dd><p>Specifies the value that <em class="parameter"><code>pname</code></em>
                    is set to.</p></dd></dl></div></div><div class="refsect1" title="Description"><a id="description"></a><h2>Description</h2><p> <code class="function">glPixelStorei</code>
        sets pixel storage modes that affect the operation of
        subsequent
        <a class="citerefentry" href="glReadPixels"><span class="citerefentry"><span class="refentrytitle">glReadPixels</span></span></a>
        as well as the unpacking of
        <a class="citerefentry" href="glTexImage2D"><span class="citerefentry"><span class="refentrytitle">glTexImage2D</span></span></a>,
        and
        <a class="citerefentry" href="glTexSubImage2D"><span class="citerefentry"><span class="refentrytitle">glTexSubImage2D</span></span></a>.
        </p><p><em class="parameter"><code>pname</code></em>
        is a symbolic constant indicating the parameter to be set, and
        <em class="parameter"><code>param</code></em>
        is the new value. The following storage parameter affects how
        pixel data is returned to client memory. This value is
        significant for
        <a class="citerefentry" href="glReadPixels"><span class="citerefentry"><span class="refentrytitle">glReadPixels</span></span></a>:
        </p><div class="variablelist"><dl><dt><span class="term">
                    <code class="constant">GL_PACK_ALIGNMENT</code>
                </span></dt><dd><p>Specifies the alignment requirements for the start
                    of each pixel row in memory. The allowable values are 1
                    (byte-alignment), 2 (rows aligned to even-numbered
                    bytes), 4 (word-alignment), and 8 (rows start on
                    double-word boundaries). The initial value is 4.</p></dd></dl></div><p>The following storage parameter affects how pixel data is
        read from client memory. This value is significant for
        <a class="citerefentry" href="glTexImage2D"><span class="citerefentry"><span class="refentrytitle">glTexImage2D</span></span></a>
        and
        <a class="citerefentry" href="glTexSubImage2D"><span class="citerefentry"><span class="refentrytitle">glTexSubImage2D</span></span></a>:
        </p><div class="variablelist"><dl><dt><span class="term">
                    <code class="constant">GL_UNPACK_ALIGNMENT</code>
                </span></dt><dd><p>Specifies the alignment requirements for the start
                    of each pixel row in memory. The allowable values are 1
                    (byte-alignment), 2 (rows aligned to even-numbered
                    bytes), 4 (word-alignment), and 8 (rows start on
                    double-word boundaries). The initial value is 4.</p></dd></dl></div></div><div class="refsect1" title="Notes"><a id="notes"></a><h2>Notes</h2><p>Pixel storage modes are client states.</p><p>
        <a class="citerefentry" href="glCompressedTexImage2D"><span class="citerefentry"><span class="refentrytitle">glCompressedTexImage2D</span></span></a>
        and
        <a class="citerefentry" href="glCompressedTexSubImage2D"><span class="citerefentry"><span class="refentrytitle">glCompressedTexSubImage2D</span></span></a>
        are not affected by <code class="function">glPixelStorei</code>.
        </p></div><div class="refsect1" title="Errors"><a id="errors"></a><h2>Errors</h2><p><code class="constant">GL_INVALID_ENUM</code> is generated if
        <em class="parameter"><code>pname</code></em> is not an accepted value.</p><p><code class="constant">GL_INVALID_VALUE</code>
        is generated if alignment is specified as other than 1, 2, 4, or 8.</p></div><div class="refsect1" title="Associated Gets"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
            <a class="citerefentry" href="glGet"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument
            <code class="constant">GL_PACK_ALIGNMENT</code> or <code class="constant">GL_UNPACK_ALIGNMENT</code>
        </p></div><div class="refsect1" title="See Also"><a id="seealso"></a><h2>See Also</h2><p>
        <a class="citerefentry" href="glReadPixels"><span class="citerefentry"><span class="refentrytitle">glReadPixels</span></span></a>,
        <a class="citerefentry" href="glCompressedTexImage2D"><span class="citerefentry"><span class="refentrytitle">glCompressedTexImage2D</span></span></a>,
        <a class="citerefentry" href="glCompressedTexSubImage2D"><span class="citerefentry"><span class="refentrytitle">glCompressedTexSubImage2D</span></span></a>,
        <a class="citerefentry" href="glTexImage2D"><span class="citerefentry"><span class="refentrytitle">glTexImage2D</span></span></a>,
        <a class="citerefentry" href="glTexSubImage2D"><span class="citerefentry"><span class="refentrytitle">glTexSubImage2D</span></span></a>
        </p></div><div class="refsect1" title="Copyright"><a id="copyright"></a><h2>Copyright</h2><p>
            Copyright © 2003-2004
            Silicon Graphics, Inc. This document is licensed under the SGI
            Free Software B License. For details, see
            <a class="ulink" href="http://oss.sgi.com/projects/FreeB/" target="_top">http://oss.sgi.com/projects/FreeB/</a>.
        </p></div></div>
